A multitude of nanoparticles including metal and oxide, semiconductor, core-shell composite architectures, and organic polymers nanoparticles have been developed to date, which exhibit novel properties and potential applications as nanotechnological building blocks. Fundamental and applied research on synthetic methods and properties of these nanoscale objects has attracted sustaining passion during the past decade as scientists strive toward perfection. However, at present, a general synthetic strategy in a continuous manner and in a way that can produce particles with size and monodispersity tuning, economy or facility, and environmental friendliness is still not available.
It is well known that controlled size and structure of nanoparticles are critical to achieve tunable physical and chemical properties of nanoparticles. For instance, in “structure sensitive” catalytic reactions there is an ideal size and morphology for metallic nanoparticles on the catalyst surface for optimum reaction conditions. Much higher catalytic efficiency can be achieved if a monomodal distributions can be produced. Moreover, advanced application of nanoparticles as building blocks for bottom-up assembly and construction of a nanoscale device requires the ability to process and maneuver particles, which makes a more strict demand for size selection.
Currently the predictable control of particle size and size distribution remains an important challenge, although some strategies have been performed and proven successfully. These strategies include controlling the concentration of capping agents, employing reverse micelles as microreactor and using dendrimer, or nano- or meso-porous matrices as encapsulation templates. However, reverse micelles and the porous templates are hard to remove after syntheses and are not ideal for producing pure and uncontaminated nanoparticles. Decomposition of organometallic precursors is also typically effective to obtain uniformly dispersed nanoparticles; however, it is still not desired in terms of cost and environmental perspectives.